title: A negative cooperativity between NADPH and adrenodoxin on binding to NADPH:adrenodoxin reductase.
abstract: Adrenodoxin stimulated the oxidation of NADPH by 1,4-benzoquinone, catalyzed by NADPH:adrenodoxin reductase. It prevented the enzyme inhibition by NADPH and formed an additional pathway of benzoquinone reduction presumably via reduced adrenodoxin. In the presence of 100-400 microM NADP+, which increased the Km of NADPH, adrenodoxin acted as a partial competitive inhibitor for NADPH decreasing its TN/Km by a limiting factor of 3. Ki of adrenodoxin decreased on the NADP+ concentration decrease and was estimated to be about 10(-8) M in the absence of NADP+.
authors.affiliation: Institute of Biochemistry, Lithuanian Academy of Sciences, Vilnius, USSR.
authors.forename: N K
authors.initials: NK
authors.lastname: Cénas
authors.forename: J A
authors.initials: JA
authors.lastname: Marcinkeviciene
authors.forename: J J
authors.initials: JJ
authors.lastname: Kulys
authors.forename: S A
authors.initials: SA
authors.lastname: Usanov
mesh_terms: D000311:Adrenal Glands / Q000201:enzymology; D000325:Adrenodoxin / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D005287:Ferredoxin-NADP Reductase / Q000378:metabolism*; D007700:Kinetics; D008928:Mitochondria / Q000201:enzymology; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D009249:NADP / Q000378:metabolism*; D010084:Oxidation-Reduction
chemical_list: D000325:Adrenodoxin; D009249:NADP; D005287:Ferredoxin-NADP Reductase; D009247:NADH, NADPH Oxidoreductases